The clearest picture yet of the Big Bang's echoes yields five numbers that explain the universe

Cosmology is sometimes pooh-poohed as more philosophy than science. It asks deep questions about nature but provides unsatisfyingly vague answers. The cosmos may be 12 billion years old, but it could be as much as 15 billion. The stars began to shine 100 million years after the Big Bang, or maybe it's a billion. "Our ideas," acknowledges Max Tegmark of the University of Pennsylvania, "have been kind of wobbly."

But much of the wobble has been fixed, thanks to a satellite known as the Wilkinson Microwave Anisotropy Probe, or WMAP. Since July 2001, WMAP has been orbiting in deep space, a...